Total phenolic contents, antioxidant activities and organic acids composition of three selected fruit extracts at different maturity Stages

The total phenolic contents (TPC), antioxidant activities and organic acid
composition of Salacca zalacca, Mangifera indica L. Chok Anan and
Baccaurea motleyana Hook. F. extracts at different maturity stages were
evaluated by using modified Folin-Ciocalteu assay at 765 nm absorbance, 2,2-
diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and HPLC RP18
column at 215 nm. TPC content ranged from 63.9 mg GAE/100g to 381.23 mg
GAE/100g, whereas the antioxidant activity ranged from 3.10% - 84.45%. The
M. indica L. Chok Anan contained malic acid and citric acid in the range of
43.897-73.396 mg/100g FW and 2.681-18.428 mg/100g FW at young to ripe
stages, respectively. B. motleyana Hook. F. contained citric acid and tartaric
acid in the range of 4.649-6.114 mg/100g FW and 3.645-4.365 mg/100g FW at
young to ripe stages, respectively. S. zalacca contained malic acid and citric
acid in the range of 4.270-17.926mg/100g FW and 0.845-3.284 mg/100g FW
at young to ripe stages, respectively. The highest TPC and antioxidant activity
were found in the young stage of S. zalacca fruit extract with lowest inhibitory
concentration (IC50) valued at 0.57 mgml-1. There was a positive linear
correlation between the TPC and antioxidant activities of the fruit extracts.
Malic acid is the predominant organic acid in M. indica L. Chok Anan and S.
zalacca, while citric acid is the predominant organic acid in B. motleyana
Hook. F. This research suggests that the studied fruits at young stage are a
better source of TPC and antioxidants. The tested fruits showed a decrease in
the concentration of organic acids with ripening.